Low acid organometallic catalyst for the production of flexible, semi-flexible and rigid polyurethane foams

ABSTRACT

The present invention relates to an improvement in flexible, semi-flexible and rigid foams formed by the catalytic reaction of an aromatic polyisocyanate, a polyol and a blowing agent and a process for preparing such polyisocyanate. The improvement resides in using an effective amount of a bismuth carboxylate or bismuth sulfonate having less than 34% free acid as the catalyst.

BACKGROUND OF THE INVENTION

[0001] Polyurethane foams produced by the catalytic reaction of apolyisocyanate with a polyol in the presence of various blowingadditives are widely known and used in fabricating parts and equipmentfor the automotive industry, as well as housing and other industries.One such blowing additive is a chlorofluorocarbon (CFC) blowing agentwhich vaporizes as a result of the reaction exotherm. The discovery thatCFC's may deplete ozone in the stratosphere has resulted in mandatesdiminishing CFC use. Production of water-blown foams, in which blowingis performed with CO₂ generated by the reaction of water with thepolyisocyanate, has therefore become increasingly important.

[0002] The production of rigid polyurethane foams is a well-known art,and as such, foams have a wide variety of industrial and commercialapplications. Rigid polyurethane foams have been used as packagingmaterials, flotation materials and various structural components. Rigidpolyurethane foam has one of the lowest thermal conductivity ratings ofany insulant, which allows efficient retention of heat or,alternatively, maintenance of a refrigerated or frozen environment.Insulating rigid polyurethane foams may be molded into many usefulappliances. The foams may be shaped into sheets of varying thickness andplaced between roofs or in floors. They also may be formed into contourshapes useful in insulating pipes and ducts. Rigid polyurethane foam canalso be applied to numerous substrates by spray foaming techniques.Spray foam applications are important particularly in such areas aswarehouses, schools and offices providing the desired insulationrequirements for heating and cooling.

[0003] Virtually all commercially manufactured polyurethane foams aremade with the aid of at least one catalyst. Catalysts are thosecompounds that help promote the reaction between an isocyanate and anisocyanate-reactive compound. The types of catalysts that are typicallyutilized in the formation of rigid polyurethane foams may differdepending on application. The ability to selectively promote either theblowing reaction (reaction of water with isocyanate to generate CO₂),the gelling reaction (reaction of polyol with isocyanate) or the trimerreaction (polymerization of isocyanate to form isocyanurate) is animportant consideration in selecting the proper catalyst.

[0004] If a catalyst promotes the blowing reaction to a high degree,much of the CO₂ will be evolved before sufficient reaction of isocyanateand polyol has occurred, and the CO₂ will bubble out of the formulation,resulting in a foam of poor quality and physical properties. Incontrast, if a catalyst too strongly promotes the gelling reaction, asubstantial portion of the CO₂ will be evolved after a significantdegree of polymerization has occurred. This foam will typically becharacterized by high density, broken or poorly defined cells, and/orother undesirable features. Finally, in those applications desiring theproduction of isocyanurate (trimer), if a catalyst does not generateenough heat (exothermic reaction) early on in the reaction, the amountof trimer that is produced will be low. Again, a poor quality foam, thistime characterized by friability, poor dimensional stability and poorfire properties, will be produced.

[0005] The following patents and articles are representative of the artin the polyurethane industry:

[0006] U.S. Pat. No. 4,200,699 discloses the formation of rigidpolyurethane foams using a catalytically effective amount of an antimonycarboxylate, a potassium carboxylate, and a zinc carboxylate incombination with tertiary amines or tin compounds.

[0007] U.S. Pat. No. 5,342,859 discloses the use of alkali metalcatalysts in the presence of excess carboxylic acid, e.g.,2-ethyl-hexoic acid to help improve the flame suppression ofpolyurethane foam by creating flame resistant amides. It also can helpto reduce the water content of in polyurethane formation.

[0008] U.S. Pat. No. 6,107,355 discloses the use of alkali and alkalineearth metal salts of mono carboxylic acids to produce polyurethanefoams. Cocatalysts consisting of tertiary amines may be used inconjunction with the metal salts.

[0009] U.S. Pat. No. 4,256,848 discloses the use of co-catalystcombinations comprised of divalent mono-mercuric salts of organic acidsand ionizable mono-organo-mercuric carboxylates as catalysts for thepreparation of polyurethanes including solid, non-cellular, and foamurethanes, both rigid and flexible.

[0010] U.S. Pat. No. 4,256,847 discloses a method for producing rigidpolyurethane foams consisting of an organic polyisocyanate, an organicpolyol, a blowing agent, and a catalyst. The catalyst suited forcatalyzing the formation of polyurethanes consists of zinc or lithiumsalts of carboxylic acids.

[0011] U.S. Pat. No. 6,242,555 discloses the use of organo bismuth,organo tin and organo lead carboxylates as catalyst types for theproduction of micro-cellular or noncellular, light stable elastomericisophorone diisocyanate based polyurethane moldings. Organobismuthcarboxylates having less than 60% free acid, preferably less than 25%and most preferably, less than 10% are disclosed.

[0012] Arenivar, J. D., Bismuth Carboxylates for PolyurethaneCatalysts., Polyurethanes, 89, Proceedings of the SPI 32^(nd) AnnualTechnical/Marketing Conference, Oct. 1-4, 1989, pp 623-627 disclose theuse of Bismuth Carboxylates for Polyurethane elastomers and the effectof added acid. Bismuth octoate and bismuth neodecanoate in the presenceof 1-4 equivalents acid were disclosed as catalytic materials.

[0013] Although organometallic catalysts have found acceptance in manycommercial coatings, adhesives, sealants, and elastomers (C.A.S.E.)applications, their use in urethane-based flexible and semi-flexiblefoams has been limited. Tertiary amines are currently the industrystandard polyurethane foam catalyst, yet their distinct odor andvolatility has had the industry searching for catalytic alternatives.

SUMMARY OF INVENTION

[0014] The present invention relates to an improvement in flexible,semi-flexible and rigid foams formed by the catalytic reaction of areaction mixture comprised of an aromatic polyisocyanate, anorganometallic catalyst, a polyol and a blowing agent. The improvementresides in a bismuth carboxylate or bismuth sulfonate having less than34% free acid as the organometallic catalyst.

[0015] Several advantages can be achieved by the use of a bismuthcarboxylate or bismuth sulfonate as the catalyst and these include:

[0016] an ability to produce flexible, semi-flexible and rigid foams ofexcellent quality

[0017] an ability to produce a foam having an excellent low value ofthermal conductivity;

[0018] an ability to produce a foam having essentially no odor; and,

[0019] an ability to reduce cell size and improve insulating properties(k-factor value).

DETAILED DESCRIPTION OF THE INVENTION

[0020] Low-density flexible, semi-flexible and rigid foams having adensity of 1-5 pounds per cubic foot (pcf) are highly cross-linkedpolymers with a closed cell structure. Each cell within this polymericmatrix maintains a high percentage of unbroken cell walls so that gasdiffusion, in and out of these cells, is very difficult. CFCs(chlorofluorocarbons), HCFCs (hydrochlorofluorocarbon), HFCs(hydrofluorocarbon), hydrocarbons or other auxiliary blowing agents areusually contained within these cells. Because these blowing agents tendto have much lower thermal conductivity than air, these rigidclosed-cell foams have a significantly lower thermal conductivity thanmost other competitive insulative materials.

[0021] In attempts to further optimize this technology, a family ofbismuth based catalysts have been identified that can, solely or inconjunction with tertiary amine catalysts, substantially reduce cellsize and the k-factor (measure of thermodynamic properties—lower thebetter) in a rigid polyurethane foam formulated with water, CFCs, HCFCs,HFCs, or hydrocarbons as conventional blowing agents. This family oforganometallic compounds has the general structure:

[M]⁺[N]⁻

[0022] where [M]⁺ corresponds to the tri-valent metal cation bismuth(Bi) and [N]⁻ corresponds to the anions of any carboxylic or sulfonicacids. These catalysts can be used to promote the reaction, solely or inconjunction with a tertiary amine or other organometallic compound,between an aromatic isocyanate functional compound, i.e., MDI, TDI andan active hydrogen-containing compound e.g., a polyol, and amine orwater especially the urethane (gelling) reaction of polyol hydroxylswith the isocyanate and the blowing reaction of water with isocyanateand/or the trimerization of the isocyanate functionality to formpolyisocyanurates.

[0023] Examples of bismuth carboxylates and sulfonates include thecarboxylates of C₅₁₅ aliphatic acids. Specifically the 2-ethyhexanoicacid (octoate) and neodecanoic acid. Examples of sulfonates includearomatic sulfonates such as p-toluenesulfonate and aliphatic sulfonatessuch as methanesulfonate and trifluoromethanesulfonate.

[0024] Examples of tertiary amines which can be utilized with thebismuth carboxylates and sulfonates include diazabicyclooctane(triethylenediamine), quinuclidine and substituted quinuclidines;substituted pyrrolizidines and substituted pyrrolidines;bisdimethylaminoethyl ether, pentamethyldiethylenetriamine, higherpermethylated polyamines, branched polyamines,2-[N-(dimethylaminoethoxyethyl)-N-methylamino]ethanol, alkoxylatedpolyamines, imidazole-boron compositions, andaminopropylbis(aminoethyl)ether compositions to produce flexible andrigid foams with enhanced foam physical properties without negativelyimpacting the existing foam processing properties (e.g. reactivityprofile, line speed, mold temperature) of existing rigid polyurethanefoam formulations.

[0025] Other tertiary amines suited for use with the bismuthcarboxylates and sulfonates include mono-ureas and bis-ureas such as2-dimethylaminoethyl urea; N,N′-bis(2-dimethylaminoethyl) urea;N,N-bis(2-dimethylaminoethyl) urea; 3-dimethyl-aminopropyl urea;N,N′-bis(3-dimethylaminopropyl) urea; N,N-bis(3-dimethylamino-propyl)urea; 1-(N-methyl-3-pyrrolidino)methyl urea;1,3-bis(N-methyl-3-pyrrolidino)-methyl urea; 3-piperidinopropyl urea;N,N′-bis(3-piperidinopropyl) urea; 3-morpholino-propyl urea;N,N′-bis(3-morpholinopropyl) urea; 2-piperidinoethyl urea;N,N′-bis(2-piperidinoethyl) urea; 2-morpholinoethyl urea; andN,N′-bis(2-morpholinoethyl) urea.

[0026] The level of bismuth catalyst employed for forming thepolyurethane will range from 0.05 to 5 parts per hundred weight partspolyol (pphp), preferably 0.2 to 3 pphp (weight basis).

[0027] The level of amine will range from 0.055 pphp when the two areuse in combination, the ratio of bismuth catalysts to the tertiary aminewill range from approximately 1:10 to 10:1 (weight basis).

[0028] These flexible, semi-flexible and rigid polyurethane foamformulations are prepared using any suitable aromatic polyisocyanateswell know in the art including, for example, phenyl diisocyanates,toluene diisocyante (TDI) and 44′-diphenylmethane diisocyanates (MDI)with % NCO content typically ranging between 20 and 50. Suitablemixtures include 2,4- and 2,6-TDI's individually or together as theircommercially available mixtures. Other suitable isocyanates are mixturesof diisocyanates known commonly as “crude MDI”, which contain4,4′-diphenylmethane diisocyanates along with other isomeric andanalogous higher polyisocyanates. Also suitable are “prepqlymers” ofthese polyisocyanate comprising a partially pre-reacted mixture of apolyisocyanate and a polyether or polyester polyol.

[0029] Illustrative of suitable polyols as a component of thepolyurethane formulation are the polyalkylene ether and polyesterpolyols. The polyalkylene ether polyols include the poly(alkylene oxide)polymers such as poly(ethylene oxide) and poly(propylene oxide) polymersand copolymers with terminal hydroxyl groups derived from polyhydriccompounds, including diols and triols; for example, among others,ethylene glycol, propylene glycol, 1,3-butane diol, 1,4-butane diol,1,6-hexane diol, neopentyl glycol, diethylene glycol, dipropyleneglycol, pentaerythritol, glycerol, diglycerol, trimethylol propane, andlike low molecular weight polyols. These polyether polyol derivationsmay be initiated with sucrose, glycerol, glycerine, aliphatic andaromatic amines, propylene glycol, Mannich bases, and/or sorbitol,individually or in combinations. Typical OH# values for these materialsmay range from 23-800.

[0030] In the practice of this invention, a single high molecular weightpolyether polyol may be used. Also, mixtures of high molecular weightpolyether polyols such as mixtures of di- and tri-functional materialsand/or different molecular weight or different chemical compositionmaterials may be used.

[0031] Useful polyester polyols include those produced by reacting adicarboxylic acid with an excess of a diol, for example, adipic acidwith ethylene glycol or butanediol, or reacting an anhydride with anexcess of a diol, such as, phthalic anhydride with diethylene glycol orreacting a lactone with an excess of a diol such as caprolactone withpropylene glycol. Typical hydroxyl number (OH#) values for thesematerials range from 160-490.

[0032] In addition to the polyether and polyester polyols and theircombinations, the masterbatches, or premix compositions, frequentlycontain a polymer polyol. Polymer polyols are used in polyurethane foamto increase the foam's resistance to deformation, i.e., to increase theload-bearing properties of the foam. Currently, two different types ofpolymer polyols are used to achieve load-bearing improvement. The firsttype, described as a graft polyol, consists of a triol in which vinylmonomers are graft copolymerized. Styrene and acrylonitrile are theusual monomers of choice. The second type, a polyurea modified polyol,is a polyol containing a polyurea dispersion formed by the reaction of adiamine and TDI. Since TDI is used in excess, some of the TDI may reactwith both the polyol and polyurea. This second type of polymer polyolhas a variant called PIPA polyol which is formed by the in-situpolymerization of TDI and alkanolamine in the polyol. Depending on theload-bearing requirements, polymer polyols may comprise 20-80% of thepolyol portion of the masterbatch.

[0033] Blowing agents such as water, methylene chloride,hydrochlorofluorocarbons, such as, trichlorofluoromethane andpentafluoropropane; hydrocarbons, liquid carbon dioxide and the like canbe used in preparing the foam formulations.

[0034] Optionally, cell stabilizers such as silicones; chain extenderssuch as ethylene glycol and butanediol; and crosslinkers such asdiethanolamine, diisopropanolamine, triethanolamine and tripropanolamineare employed in foam formulations.

[0035] A general polyurethane rigid foam formulation having a 0.5-5.0lb/ft³ (8.0-80.2 kg/m³) density containing a organometallic catalyst,composition according to the invention, would comprise the followingcomponents in parts by weight (pbw): Parts by Weight Rigid FoamFormulation (pphp) Polyol 100 Silicone Surfactant 1-4 Blowing Agent 2-35 Catalyst 0.01-10   Co-Catalysts 0.01-10   Water 0-5 IsocyanateIndex  70-300

[0036] A general polyurethane flexible foam formulation having a densityof 1-3 lb/ft³ (16-48 kg/m³) (e.g., automotive seating) containingcatalysts such as the bismuth carboxylate catalyst compositionsaccording to the invention would comprise the following components inparts by weight (pbw): Parts by Weight Flexible Foam (pphp) ConventionalPolyol  20-100 (˜5000 MW Triol) Co-Polymer Polyol 60-0  SiliconeSurfactant   1-2.5 Blowing Agent   2-4.5 Crosslinker 0.5-3   Catalyst0.1-10  Isocyanate Index  70-115

[0037] The term conventional polyol and polymer polyol is intended torefer to a polyol that is used as the base polyol for formulation offlexible molded foam. It is void of grafts using Styrene Acrylonitrile(SAN). A co-polymer is one that has SAN grated onto the conventional orbase polyol. This helps to build load in the system.

[0038] The following examples are given to illustrate variousembodiments of the invention and should not be interpreted as limitingin any way.

EXAMPLE 1 Comparison of Bismuth Octoate or Bismuth Neodecanoate VersesTertiary Amine Catalysts in Rigid Foam Formation

[0039] A conventional polyurethane foam was prepared using theformulation for an HCFC 141 b Appliance Foam application listed below:Parts by Weight Component (pphp) Polyol Blend 100.0 Water 2.0 HCFC 141b37.0 Catalyst -Varied DC 5700 3.0 Polymeric MDI 140 Index

[0040] Machine scale testing was completed on the above-mentionedformulations using a Cannon Type A-40/20 high-pressure machine with athroughput of 25 to 30 lbs/min. The polyol, water, HCFC 141b, surfactantand catalysts were loaded into the resin day tank and agitated. Thepolymeric MDI was loaded into the isocyanate day tank. Both tanks werethen pressured with nitrogen to keep constant head pressure throughoutthe experiment. The polymeric MDI was maintained at 85° F., while theresin was held constant at 80° F. Both the isocyanate-side and theresin-side pour pressures were maintained at 2000 psi throughout theexperiment. Foams were set into a Lantzen panel mold (200 cm×20 cm×5 cm)at a constant temperature of 120° F. The foam was allowed to flowvertically in the Lantzen panel in order to measure flow and subsequentoverall final foam density. In addition to minimum fill weights, variousover-packed foams were produced for physical testing (K-factor andaverage cell size count). The tertiary amine catalysts (PC5+PC41 vs.bismuth tris 2-ethylhexanoic acid (bismuth octoate) vs. bismuth trisneodecanoic acid (bismuth NDA) were compared at varying use levels, butall maintaining similar reactivity profiles (cream, string gel and tackfree times).

[0041] Table I lists the final foam physical properties obtained usingthe catalysts PC5+PC 41, Bismuth Octoate, Bismuth Neodecanoate. In allcases, the foam reactivity was matched by monitoring free rise pourswhich allowed for the easy measurement of cream, string gel and tackfree times. Free rise densities were also measured at this time. Thefoams tested met standard ASTM specifications, % Closed Cell—ASTM D2856, Dimensional Stability—ASTM D 2126, K-Factor—ASTM C 177,Compressive Strength—ASTM D 1621. Cell size was determined with the aidof a Hitachi solid-state color video camera attached to a Nikon SMZ—2Tmicroscope. Rigid samples were cut down to 0.25 in. widths and analyzedat 60× magnification. TABLE I PC 5:PC 41 Bismuth Bismuth Catalyst AminesOctoate NDA Use Level parts per hundred 1.2:1.0 1.5 1.65 parts polyol byweight (pphp) Processing Conditions Iso. Temp. (° F.) 85 85 85 ResinTemp. (° F.) 80 80 80 Pour Pressure (Iso = Resin, psi) 2000 2000 2000Mold Temperature (° F.) 120 120 120 Time to Demold (min.) 3.0 3.0 3.0Reactivity Cream 3.0 8.0 7.0 String Gel 27.0 32.0 35.0 Tack Free 44.045.0 44.0 Min. Fill Density (pcf) 1.87 1.85 1.88 24 hr K-factor (BTU ·in/ft² · h · ° F.) Density = 2.0 0.132 0.123 0.123 Density = 2.1 0.1310.121 0.125 Average Cell Size (microns) 330 250 220 % Closed Cell 82 8786

[0042] The data in Table I show that by using either bismuth octoate orbismuth neodecanoate in place of the standard tertiary amine catalysts(e.g. PC5 and PC 41), that it is possible to positively impact both thecell size and k-factor of the resulting foam without negativelyimpacting the existing processing conditions. K factor differences of0.003 or greater are considered statistically significant, thus thebismuth results are substantially improved relative to the PC5/PC41amine control run. Additionally, the data demonstrate that use of themetal carboxylates can lengthen the cream time without affecting thetack free time. This effectively translates to improved flowcharacteristics and better mold fill. The use of bismuth octoate orbismuth neodecanoate produces comparable reactivities at similar minimumfill densities to that of tertiary amines with the added benefit of asignificantly reduced cell size.

EXAMPLE 2 Effect of Catalysts (PC 5/PC 41 vs. Bismuth Neodecanoate)

[0043] A conventional (rigid) spray polyurethane foam was prepared usingthe formulation listed below for the purpose of determining the effectof the catalysts (PC5+PC41 vs. bismuth NDA) at varying use levels, butmaintaining similar reactivity profiles (cream, string gel and tack freetimes). Parts by Weight Component (pphp) Polyol Blend 100.0 Water 0.40HCFC 141b 21.0 Catalyst 0.1-1.0 DC193 2.0 Polymeric MDI 190 Index

[0044] Machine scale testing was completed on the above-mentionedformulation using a Gusmer VH3000 high-pressure variable ratio spraymachine with a throughput of 10 to 20 lbs/min. The Polyol, Water, HCHC141b, surfactant and catalysts were loaded into the resin day tank andagitated. The polymeric MDI was loaded into the isocyanate day tank.Both tanks were then pressured with nitrogen to keep constant headpressure throughout the experiment. Both the isocyanate-side and theresin-side pour pressures were maintained at 1000 psi and sprayedthrough a Gusmer Model GX-7 spray Gun set-up with a # 1 module(Diameter=0.125 in.) and a 70 tip round spray pattern (patterndiameter=12 inches at 24 inches above substrate). Both the isocyanateand resin hose heaters were maintained at 80° F. Atmospheric conditionsfor the spray environment and substrate were maintained at 75° F. and50% relative humidity by spraying inside a temperature and humiditycontrolled spray booth. The resulting polyurethane foam was sprayed ontostandard cardboard that was conditioned inside the spray booth.

[0045] Table II lists the final foam physical properties obtained usingthe catalysts PC5+PC 41 and bismuth NDA. In all cases, the foamreactivity was matched by monitoring hand-mixed free rise pours whichallowed for the easy measurement of cream, string gel and tack freetimes. Free rise densities were also measured at this time. The foamstested met standard ASTM specifications, % Closed Cell—ASTM D 2856,Dimensional Stability—ASTM D 2126, K-Factor—ASTM C 177, CompressiveStrength—ASTM D 1621. Cell size was determined with the aid of a Hitachisolid-state color video camera attached to a Nikon SMZ—2T microscope.Rigid samples were cut down to 0.25 in. widths and analyzed at 60×magnification. TABLE II Catalyst PC5:/DMEA Bismuth Neodecanoate UseLevel (pphp) 0.8:/3.0 1.2 Reactivity Cream 4.0 6.0 String Gel 11.0 13.0Tack Free 17.0 16.0 24 hr K-factor (BTU · in/ft² · h · ° F.) 0.133 0.125Density (pcf) 2.47 2.42 Average Cell Size (microns) 235 217

[0046] The data in Table II demonstrates the effectiveness of usingbismuth neodecanoate in place of the standard amine catalysts (e.g. PC5and dimethylethanol amine) (DMEA)). Though the reactivity profileremained more or less unchanged, the bismuth catalyst positivelyimpacted both the average cell size and k-factor of the resulting foam.K factor differences of 0.003 or greater are considered statisticallysignificant, thus the bismuth results are substantially improvedrelative to the tertiary amine control example.

EXAMPLE 3 Effect of Acid in Organometallic Bismuth CatalyzedPolyurethane Flexible Foam

[0047] In this example, a polyurethane foam was prepared in aconventional manner substituting various catalyst packages. Thisexperiment evaluated the effect of excess 2-ethylhexanoic acid (2 EHA)on the ability of bismuth tris 2-ethylhexanoic acid (bismuth octoate) tocatalyze and produce a flexible polyurethane foam of good quality. Theconditions, starting materials and catalytic sites (moles of bismuth)were kept constant throughout these experiments.

[0048] Conventional hand-mix techniques were used to prepare the desired1.9-2.0 pcf density molded flexible foam. Table III lists the physicalproperties obtained using the various types of catalysts. The controlcatalyst package consisted of the industrial standard amine package,Dabco 33LV and Dabco BL 11. To compare the effect of excess free acid ona commercial catalyst (Bicat H, 18 wt % Bi, 45 wt % free acid) wascompared to a low acid bismuth catalyst.

[0049] All catalysts were based on CATALYST 1 (28.2 wt % Bi, 9 wt % freeacid) and diluted with increasing concentrations of 2-EHA. The foamswere made in a heated test block mold at 160° F. The catalyst package ofDabco 33LV and BL 11 were used to establish the desired reactivity andfoam performance baseline. CATALYST 1, the lowest free acid bismuthoctoate, and Polycat 77 were then tested at varying concentrations untilthe foam reactivity was matched. This was determined by monitoring theextrusion time, which measures the reaction and provides some indicationof extent of cure. Once the molar concentration of bismuth (plus aconstant amount of Polycat 77) necessary to catalyze the reaction at thesame rate as Dabco 33LV and BL 11 was determined, all bismuth catalystswere then tested at equivalent bismuth concentrations and varying freeacid concentrations, along with the Polycat 77. The foams tested metstandard specifications listed in ASTM D 3453-91 and the tests wereperformed using ASTM designation D 3574-95.

[0050] The polyurethane formulation in parts by weight was: TABLE IIIParts by Weight Component (pphp) Pluracol E-1509 75 E 851 25 DC 5164 0.2DC 5169 0.6 DEOA-LF 1.4 Dabco BL11 See table I Dabco 33LV See table ICatalyst See table I PC77 See table I Water 4.07 TDI 80 100 Index

[0051] TABLE III Catalyst/use level (php) 33 LV/ CAT 1/ CAT 3/ CAT 5/0.32 1.0 1.15 1.25 BL 11/ BICAT H/1.56 PC 77/ PC77/ PC77/ CAT 6/1.3 0.08PC 77/0.32 0.32 0.32 0.32 PC77/0.32 Moles Bi added 0.0 1.35 1.35 1.351.35 1.35 (10⁻⁰³) Wt % Free Acid 0.0 45.0 9.0 24.0 34.0 39.0 MoldReactivity Extrusion time 46 49 48 48 48 49 (sec) String Gel (sec) 63143 65 66 77 139 Density (pcf) 1.88 FOAM 1.94 1.89 2.01 FOAM COLLAPSECOLLAPSE Airflow (SCFM) 2.1 1.7 1.7 1.8 Compression Set JWS (% ht loss)27 34 34 38 50% HACS 32 30 30 32 (% ht loss) Foam Tear 10 19 20 16 PeakLoad (N/m) IFD at 25% (lbf) 32 34 35 35 IFD at 65% (lbf) 84 90 90 91Return to 25% 26 27 27 27 (lbf) Ball Rebound 53 53 55 52 (%)

[0052] The data in Table III clearly demonstrate how the presence ofexcess free acid can adversely affect the ability of a metalcarboxylate, in this case bismuth octoate, to catalyze and produce anacceptable flexible polyurethane foam. As evident by this data, anexcess of greater than 34 wt % free 2-EHA was directly responsible forthe failure of the commercial bismuth catalysts Bicat H, and theexperimental CATALYST 6 to produce a foam that was acceptable and thatcould be measured for foam physical properties. The data alsodemonstrate that physical properties can be maintained, and in somecases, slightly improved over a traditional tertiary amine basedcatalyst system.

[0053] It is interesting that in the production of a flexible or rigidfoam vis-à-vis a polyurethane elastomer as described in Article: Proc.SPI Annu. Tech/Mark. Conf. (1989), 32^(nd) (Polyurethanes 89), 623-7,Bismuth Carboxylates for Polyurethane Catalysts, that low acid levels incombination with a bismuth carboxyl produce good foams while the use ofan high levels, e.g., 47 to 73 wt % free acid (calculations based onthis literature's assertion that a sample of bismuth pivalate (bismuthtris-trimethyl acetic acid) performance increases in the presence of 1to 3 equivalents of excess free acid) significantly improves the rate ofreaction, as well as the elastomer physical properties.

EXAMPLE 4 Effect of Neodecanoic Acid (Nda) on Bismuth Tris NeodecanoicAcid in Polyurethane Foam Preparation

[0054] In this example, a polyurethane foam was prepared in aconventional manner substituting various catalyst packages. Thisexperiment evaluated the effect excess neodecanoic acid (NDA) has on theability of bismuth tris neodecanoic acid (bismuth NDA) to catalyze andproduce a flexible polyurethane foam of good quality. The polyurethaneformulation in parts by weight was: Parts by Weight Component (pphp)Pluracol E1509 75 E 851 25 DC 5164 0.2 DC 5169 0.6 DEOA-LF 1.4 Dabco BL11 0.08 Catalyst See table 2 Water 4.07 TDI 100 Index

[0055] Conventional hand-mix techniques were used to make the desiredfree rise foams. Table IV list the reactivity profile obtained usingvarious types of catalysts. The control catalyst package consisted ofthe amine package Dabco 33LV and BL 11. To compare the effect of anorganometallic catalyst with excess free acid the following experimentalcatalysts were supplied by Shepherd Chemical Co., LB2174-2, -3, -4, -5,-7 and LB2304-2, -3 were chosen. The foams were made in the standardhand-mix free rise method. The catalyst package of Dabco 33LV and BL 11were used to establish the desired reactivity and foam performancebaseline. Catalyst LB2174-2, the lowest free acid bismuth NDA, was thentested at varying concentrations until the foam reactivity was matched.Dabco BL 11 was kept constant throughout these experiments. Once themolar concentration of bismuth necessary to catalyze the reaction at thesame rate as Dabco 33LV and BL 11 was determined, all bismuth catalystswere then tested at equivalent bismuth concentrations and varying freeacid concentrations. TABLE IV Catalyst Dabco 33 LV 2174-2 2174-7 2174-52174-4 2174-3 2304-3 2304-2 0.32 2.0 2.0 2.0 2.0 2.0 2.2 2.5 parts partsparts parts parts parts parts parts Moles Bi 0.00 1.93 1.93 1.93 1.931.93 1.93 1.93 (10⁻³) Wt % 0.0 3.1 13.8 22.7 28.9 31.9 34.7 44.3 FreeAcid Reactivity Cup 1 16 18 19 19 21 22 24 28 (sec) Cup 2 46 46 47 47 4952 57 63 (sec) String 68 71 71 71 73 74 Foam Foam Gel (sec) CollapseCollapse Full Rise 152 97 96 97 99 98 (sec) Full Rise 413 395 399 396397 392 (mm)

[0056] The data in Table IV clearly demonstrates that the presence ofexcess free acid can adversely effect the ability of a metalcarboxylate, in this case bismuth neodecanoate, to catalyze and producean acceptable flexible polyurethane foam. The conditions, startingmaterials and catalytic sites (moles of bismuth) were kept constantthroughout these experiments. As evident by this data, an excess ofgreater than 34.7 wt % free NDA was directly responsible for the failureof the bismuth catalysts, experimental samples 2304-3 and 2304-2, toproduce a foam that was acceptable (non-collapsed).

[0057] Finally, it should be noted that while a co-catalyst (gellingand/or blowing) is typically used in conjunction with these low acidorganometallic catalysts that these products can be used as solecatalysts depending on the properties/reactivity ratio that is desired.

1. In a flexible, semi-flexible or rigid polyurethane foam formed by thecatalytic reaction of a reaction mixture comprised of an aromaticpolyisocyanate, an organometallic catalyst, a polyol and a blowingagent, the improvement which resides in a bismuth carboxylate or bismuthsulfonate having less than 34% free acid as the organometallic catalyst.2. The flexible, semi-flexible or rigid polyurethane foam of claim 1wherein the organometallic catalyst is a bismuth carboxylate.
 3. Theflexible, semi-flexible or rigid polyurethane foam of claim 2 whereinthe aromatic polyisocyanate is selected from the group consisting ofdiphenylmethane diisocyanate and toluenediisocyanate.
 4. The flexible,semi-flexible or rigid polyurethane foam of claim 1 wherein the bismuthcarboxylate employed in the reaction mixture is in an amount from 0.05to 5 parts per hundred parts polyol by weight.
 5. The flexible,semi-flexible or rigid polyurethane foam of claim 1 wherein thecarboxylate is derived from a C₅₋₁₅ aliphatic carboxylic acid.
 6. Theflexible, semi-flexible or rigid polyurethane foam of claim 5 whereinthe carboxylic acid is selected from the group consisting of2-ethylhexanoic acid and neodecanoic acid.
 7. The flexible,semi-flexible or rigid polyurethane foam of claim 6 wherein a tertiaryamine catalyst has been included in the reaction mixture.
 8. Theflexible, semi-flexible or rigid polyurethane foam of claim 7 whereinthe ratio of bismuth carboxylate to tertiary amine catalyst is from 1:10to 10:1 on a weight basis.
 9. The flexible, semi-flexible or rigidpolyurethane foam of claim 8 wherein the tertiary amine is selected fromthe consisting of triethylenediamine, pentamethyldipropylenetriamine andbis(dimethylaminoethyl)ether.
 10. The flexible, semi-flexible or rigidpolyurethane foam of claim 8 wherein the tertiary amine is selected fromgroup consisting of 2-dimethylaminoethyl urea;N,N′-bis(2-dimethylaminoethyl) urea; N,N-bis(2-dimethylaminoethyl) urea;3-dimethylaminopropyl urea; N,N′-bis(3-dimethylaminopropyl) urea;1-(N-methyl-3-pyrrolidino)methyl urea;1,3-bis(N-methyl-3-pyrrolidino)-methyl urea; 3-piperidinopropyl urea;N,N′-bis(3-piperidinopropyl) urea; 3-morpholino-propyl urea;N,N′-bis(3-morpholinopropyl) urea; 2-piperidinoethyl urea;N,N′-bis(2-piperidinoethyl) urea; 2-morpholinoethyl urea; andN,N′-bis(2-morpholinoethyl) urea.
 11. The flexible, semi-flexible orrigid polyurethane foam of claim 8 wherein the tertiary amine isselected from the group consisting of 3-dimethyl-aminopropyl urea;N,N′-bis(3-dimethylaminopropyl) urea; and1-(N-methyl-3-pyrrolidino)methyl urea.
 12. In a process for producing aflexible, semi-flexible or rigid polyurethane foam by the catalyticreaction of a reaction mixture comprised of an aromatic polyisocyanate,an organometallic catalyst, a polyol and a blowing agent, theimprovement which resides in employing a bismuth carboxylate or bismuthsulfonate having less than 34% free acid as the organometallic catalyst.13. The process for producing the flexible, semi-flexible or rigidpolyurethane foam of claim 12 wherein the organometallic catalystemployed is a bismuth carboxylate.
 14. The process for producing theflexible, semi-flexible or rigid polyurethane foam of claim 13 whereinthe aromatic polyisocyanate is selected from the group consisting ofdiphenylmethane diisocyanate and toluenediisocyanate.
 15. The processfor producing the flexible, semi-flexible or rigid polyurethane foam ofclaim 14 wherein the bismuth carboxylate is employed in an amount from0.05 to 5 parts per hundred parts polyol by weight.
 16. The process forproducing the flexible, semi-flexible or rigid polyurethane foam ofclaim 15 wherein the bismuth carboxylate is derived from a C₅₋₁₅aliphatic carboxylic acid.
 17. The process for producing the flexible,semi-flexible or rigid polyurethane foam of claim 16 wherein thecarboxylic acid is selected from the group consisting of 2-ethylhexanoicacid and neodecanoic acid.
 18. The process for producing the flexible,semi-flexible or rigid polyurethane foam of claim 17 wherein a tertiaryamine catalyst has been employed in the reaction mixture.
 19. Theprocess for producing the flexible, semi-flexible or rigid polyurethanefoam of claim 18 wherein the ratio of bismuth carboxylate to tertiaryamine catalyst is from 1:10 to 10:1 on a weight basis.
 20. The processfor producing the flexible, semi-flexible or rigid polyurethane foam ofclaim 19 wherein the tertiary amine is selected from the groupconsisting of triethylenediamine, pentamethyldipropylenetriamine andbis(dimethylaminoethyl)ether.
 21. The flexible, semi-flexible or rigidpolyurethane foam of claim 18 wherein the tertiary amine is selectedfrom group consisting of 2-dimethylaminoethyl urea;N,N′-bis(2-dimethylaminoethyl) urea; N,N-bis(2-dimethylaminoethyl) urea;3-dimethylaminopropyl urea; N,N′-bis(3-dimethylaminopropyl) urea;1-(N-methyl-3-pyrrolidino)methyl urea;1,3-bis(N-methyl-3-pyrrolidino)-methyl urea; 3-piperidinopropyl urea;N,N′-bis(3-piperidinopropyl) urea; 3-morpholino-propyl urea;N,N′-bis(3-morpholinopropyl) urea; 2-piperidinoethyl urea;N,N′-bis(2-piperidinoethyl) urea; 2-morpholinoethyl urea; andN,N′-bis(2-morpholinoethyl) urea.
 22. The flexible, semi-flexible orrigid polyurethane foam of claim 21 wherein the tertiary amine isselected from the group consisting of 3-dimethyl-aminopropyl urea;N,N′-bis(3-dimethylaminopropyl) urea; and1-(N-methyl-3-pyrrolidino)methyl urea.